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As the name implies, no rectification is used in the electroless process and therefore there are no throwing power problems. Consequently in a well-agitated solution the deposit forms a uniform coating over the whole item regardless of its shape. That is perhaps the biggest advantage of the electroless nickel process. The properties of the deposit change with the phosphorus or boron content and tah is detailed below.
This is the hardest of the P deposits (around 700VHN) and with great care can be heat treated to provide a hardness of about 900VHN. The deposit can anneal very easily. Corrosion resistant to alkaline environments.
Applications: Plating aluminium items to harden the outer surface.
Good wear and low frictional properties Hardness as plated 600 to 650VHN. Hardness can be improved by heat treatment at 400 deg C for one hour (to around 800VHN).
Applications:- Automotive parts.
The softest deposit, (about 500VHN) can be polished for satellite mirrors. Can be heat treated to around 700VHN. Corrosion resistant to acidic environments.
Applications:- N Sea Oil platforms, ball valves, etc
Hard thin coating (max about 5 microns). Good contact resistance and solderable. Has been used to replace gold on circuit boards.
pplications: Mainly in the electronics industry
Engineering deposit, matt dark grey colour, dendritic growth. Doesn’t provide good corrosion protection (need high P undercoat) Hardness around 1100VHN. Good wear resistance and very low coefficient of friction
Applications: Mating, rubbing surfaces, e.g. Pistons, cylinders, etc.